An intensive investigation of fatty acid desaturation in bacilli is continuing using Bacillus megaterium as the experimental organism. The overall objectives of the project include the elucidation of the mechanisms by which bacilli adaptively adjust the level of unsaturated fatty acids in their membrane lipids in response to changes in environmental temperature, the mechanisms by which unsaturated fatty acids are incorporated and utilized in membrane lipids and the characterization of the desaturation systems of bacilli in cell-free preparations.